The invention relates to a method and apparatus for filtering data. Preferably, the invention is used in an image data noise filter. The invention also relates to a television receiver comprising such a noise filter.
EP-A-0,581,059 discloses a method of filtering noise in television or video signals by means of a noise reduction circuit having a first input which receives the input signal, and a second input which receives a low-frequency part of a field delayed output signal of the noise reduction circuit. A decimation filter is present between an output of the noise reduction circuit and the field delay to reduce the data rate of the output signal of the noise reduction circuit. More specifically, the bandwidth is reduced by a factor 2, the data rate is reduced by the same factor, and the bit resolution is reduced from 8 bits to 7 bits. An interpolation filter is present between the field delay and the second input of the noise reduction circuit. The presence of the decimation filter and the interpolation filter allows the use of a field delay with a reduced storage capacity. When it is attempted to obtain a further reduction of the required storage capacity, disturbing artifacts occur when the prior art techniques are used.